by the way

Từ điển Oxford Advanced Learner 8th

by the ˈway idiom
(also by the ˈby/ˈbye) (informal)used to introduce a comment or question that is not directly related to what you have been talking about
• By the way, I found that book you were looking for.
• What's the time, by the way?
•Oh by the way, if you see Jackie, tell her I'll call her this evening.
Main entry: ↑way_idiom